/*
 * Copyright 2013-2018 Lilinfeng.
 *  
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *  
 *      http://www.apache.org/licenses/LICENSE-2.0
 *  
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.phei.netty.protocol.websocket.server;

import static io.netty.handler.codec.http.HttpHeaders.isKeepAlive;
import static io.netty.handler.codec.http.HttpHeaders.setContentLength;
import static io.netty.handler.codec.http.HttpResponseStatus.BAD_REQUEST;
import static io.netty.handler.codec.http.HttpVersion.HTTP_1_1;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.DefaultFullHttpResponse;
import io.netty.handler.codec.http.FullHttpRequest;
import io.netty.handler.codec.http.FullHttpResponse;
import io.netty.handler.codec.http.websocketx.CloseWebSocketFrame;
import io.netty.handler.codec.http.websocketx.PingWebSocketFrame;
import io.netty.handler.codec.http.websocketx.PongWebSocketFrame;
import io.netty.handler.codec.http.websocketx.TextWebSocketFrame;
import io.netty.handler.codec.http.websocketx.WebSocketFrame;
import io.netty.handler.codec.http.websocketx.WebSocketServerHandshaker;
import io.netty.handler.codec.http.websocketx.WebSocketServerHandshakerFactory;
import io.netty.util.CharsetUtil;

import java.util.logging.Level;
import java.util.logging.Logger;

/**
 * @author lilinfeng
 * @date 2014年2月14日
 * @version 1.0
 */
public class WebSocketServerHandler extends SimpleChannelInboundHandler<Object> {
    private static final Logger logger = Logger
	    .getLogger(WebSocketServerHandler.class.getName());

    private WebSocketServerHandshaker handshaker;

    @Override
    public void messageReceived(ChannelHandlerContext ctx, Object msg)
	    throws Exception {
	// 传统的HTTP接入
	if (msg instanceof FullHttpRequest) {
	    handleHttpRequest(ctx, (FullHttpRequest) msg);
	}
	// WebSocket接入
	else if (msg instanceof WebSocketFrame) {
	    handleWebSocketFrame(ctx, (WebSocketFrame) msg);
	}
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
	ctx.flush();
    }

    private void handleHttpRequest(ChannelHandlerContext ctx,
	    FullHttpRequest req) throws Exception {

	// 如果HTTP解码失败，返回HHTP异常
	if (!req.getDecoderResult().isSuccess()
		|| (!"websocket".equals(req.headers().get("Upgrade")))) {
	    sendHttpResponse(ctx, req, new DefaultFullHttpResponse(HTTP_1_1,
		    BAD_REQUEST));
	    return;
	}

	// 构造握手响应返回，本机测试
	WebSocketServerHandshakerFactory wsFactory = new WebSocketServerHandshakerFactory(
		"ws://localhost:8080/websocket", null, false);
	handshaker = wsFactory.newHandshaker(req);
	if (handshaker == null) {
	    WebSocketServerHandshakerFactory
		    .sendUnsupportedWebSocketVersionResponse(ctx.channel());
	} else {
	    handshaker.handshake(ctx.channel(), req);
	}
    }

    private void handleWebSocketFrame(ChannelHandlerContext ctx,
	    WebSocketFrame frame) {

	// 判断是否是关闭链路的指令
	if (frame instanceof CloseWebSocketFrame) {
	    handshaker.close(ctx.channel(),
		    (CloseWebSocketFrame) frame.retain());
	    return;
	}
	// 判断是否是Ping消息
	if (frame instanceof PingWebSocketFrame) {
	    ctx.channel().write(
		    new PongWebSocketFrame(frame.content().retain()));
	    return;
	}
	// 本例程仅支持文本消息，不支持二进制消息
	if (!(frame instanceof TextWebSocketFrame)) {
	    throw new UnsupportedOperationException(String.format(
		    "%s frame types not supported", frame.getClass().getName()));
	}

	// 返回应答消息
	String request = ((TextWebSocketFrame) frame).text();
	if (logger.isLoggable(Level.FINE)) {
	    logger.fine(String.format("%s received %s", ctx.channel(), request));
	}
	ctx.channel().write(
		new TextWebSocketFrame(request
			+ " , 欢迎使用Netty WebSocket服务，现在时刻："
			+ new java.util.Date().toString()));
    }

    private static void sendHttpResponse(ChannelHandlerContext ctx,
	    FullHttpRequest req, FullHttpResponse res) {
	// 返回应答给客户端
	if (res.getStatus().code() != 200) {
	    ByteBuf buf = Unpooled.copiedBuffer(res.getStatus().toString(),
		    CharsetUtil.UTF_8);
	    res.content().writeBytes(buf);
	    buf.release();
	    setContentLength(res, res.content().readableBytes());
	}

	// 如果是非Keep-Alive，关闭连接
	ChannelFuture f = ctx.channel().writeAndFlush(res);
	if (!isKeepAlive(req) || res.getStatus().code() != 200) {
	    f.addListener(ChannelFutureListener.CLOSE);
	}
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
	    throws Exception {
	cause.printStackTrace();
	ctx.close();
    }
}
